def get_trees(world, slopes):
	result = 1

	for dx, dy in slopes:
		trees = 0
		x = 0
		y = 0

		while y < len(world):
			if world[y][x] == '#':
				trees += 1
			x = (x + dx) % len(world[y])
			y += dy

		result *= trees

	return result


with open('input.txt') as fh:
	world = [line.rstrip() for line in fh]

print(get_trees(world, [(1, 3)]))
print(get_trees(world, [(1, 1), (3, 1), (5, 1), (7, 1), (1, 2)]))